/*
** $Id: ltm.c,v 2.38.1.1 2017/04/19 17:39:34 roberto Exp $
** Tag methods
** See Copyright Notice in lua.h
*/

#define ltm_c
#define LUA_CORE

#include "lprefix.h"

#include <string.h>

#include "lua.h"

#include "ldebug.h"
#include "ldo.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lvm.h"

static const char udatatypename[] = "userdata";

LUAI_DDEF const char *const luaT_typenames_[LUA_TOTALTAGS] = {
    "no value",
    "nil", "boolean", udatatypename, "number",
    "string", "table", "function", udatatypename, "thread",
    "proto" /* this last case is used for tests only */
};

void luaT_init(lua_State *L)
{
  static const char *const luaT_eventname[] = {/* ORDER TM */
                                               "__index", "__newindex",
                                               "__gc", "__mode", "__len", "__eq",
                                               "__add", "__sub", "__mul", "__mod", "__pow",
                                               "__div", "__idiv",
                                               "__band", "__bor", "__bxor", "__shl", "__shr",
                                               "__unm", "__bnot", "__lt", "__le",
                                               "__concat", "__call"};
  int i;
  for (i = 0; i < TM_N; i++)
  {
    G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
    luaC_fix(L, obj2gco(G(L)->tmname[i])); /* never collect these names */
  }
}

/*
** function to be used with macro "fasttm": optimized for absence of
** tag methods
*/
const TValue *luaT_gettm(Table *events, TMS event, TString *ename)
{
  const TValue *tm = luaH_getshortstr(events, ename);
  lua_assert(event <= TM_EQ);
  if (ttisnil(tm))
  {                                          /* no tag method? */
    events->flags |= cast_byte(1u << event); /* cache this fact */
    return NULL;
  }
  else
    return tm;
}

const TValue *luaT_gettmbyobj(lua_State *L, const TValue *o, TMS event)
{
  Table *mt;
  switch (ttnov(o))
  {
  case LUA_TTABLE:
    mt = hvalue(o)->metatable;
    break;
  case LUA_TUSERDATA:
    mt = uvalue(o)->metatable;
    break;
  default:
    mt = G(L)->mt[ttnov(o)];
  }
  return (mt ? luaH_getshortstr(mt, G(L)->tmname[event]) : luaO_nilobject);
}

/*
** Return the name of the type of an object. For tables and userdata
** with metatable, use their '__name' metafield, if present.
*/
const char *luaT_objtypename(lua_State *L, const TValue *o)
{
  Table *mt;
  if ((ttistable(o) && (mt = hvalue(o)->metatable) != NULL) ||
      (ttisfulluserdata(o) && (mt = uvalue(o)->metatable) != NULL))
  {
    const TValue *name = luaH_getshortstr(mt, luaS_new(L, "__name"));
    if (ttisstring(name))           /* is '__name' a string? */
      return getstr(tsvalue(name)); /* use it as type name */
  }
  return ttypename(ttnov(o)); /* else use standard type name */
}

void luaT_callTM(lua_State *L, const TValue *f, const TValue *p1,
                 const TValue *p2, TValue *p3, int hasres)
{
  ptrdiff_t result = savestack(L, p3);
  StkId func = L->top;
  setobj2s(L, func, f);      /* push function (assume EXTRA_STACK) */
  setobj2s(L, func + 1, p1); /* 1st argument */
  setobj2s(L, func + 2, p2); /* 2nd argument */
  L->top += 3;
  if (!hasres)                 /* no result? 'p3' is third argument */
    setobj2s(L, L->top++, p3); /* 3rd argument */
  /* metamethod may yield only when called from Lua code */
  if (isLua(L->ci))
    luaD_call(L, func, hasres);
  else
    luaD_callnoyield(L, func, hasres);
  if (hasres)
  { /* if has result, move it to its place */
    p3 = restorestack(L, result);
    setobjs2s(L, p3, --L->top);
  }
}

int luaT_callbinTM(lua_State *L, const TValue *p1, const TValue *p2,
                   StkId res, TMS event)
{
  const TValue *tm = luaT_gettmbyobj(L, p1, event); /* try first operand */
  if (ttisnil(tm))
    tm = luaT_gettmbyobj(L, p2, event); /* try second operand */
  if (ttisnil(tm))
    return 0;
  luaT_callTM(L, tm, p1, p2, res, 1);
  return 1;
}

void luaT_trybinTM(lua_State *L, const TValue *p1, const TValue *p2,
                   StkId res, TMS event)
{
  if (!luaT_callbinTM(L, p1, p2, res, event))
  {
    switch (event)
    {
    case TM_CONCAT:
      luaG_concaterror(L, p1, p2);
    /* call never returns, but to avoid warnings: */ /* FALLTHROUGH */
    case TM_BAND:
    case TM_BOR:
    case TM_BXOR:
    case TM_SHL:
    case TM_SHR:
    case TM_BNOT:
    {
      lua_Number dummy;
      if (tonumber(p1, &dummy) && tonumber(p2, &dummy))
        luaG_tointerror(L, p1, p2);
      else
        luaG_opinterror(L, p1, p2, "perform bitwise operation on");
    }
    /* calls never return, but to avoid warnings: */ /* FALLTHROUGH */
    default:
      luaG_opinterror(L, p1, p2, "perform arithmetic on");
    }
  }
}

int luaT_callorderTM(lua_State *L, const TValue *p1, const TValue *p2,
                     TMS event)
{
  if (!luaT_callbinTM(L, p1, p2, L->top, event))
    return -1; /* no metamethod */
  else
    return !l_isfalse(L->top);
}
